I agree with Robbie's overall assesment (big surprise) but I would ask Robbie this: Yes, if he's sending 20k hits to 50 differant sponsers then I totally get your point (he'll never make significant sales). BUT: what if he were sending those 20k hits - even if they came from a 100 differant blogs - to the SAME sponser? Then he would make more sales, yes? Assuming the sponser was good, of course.
This is what I plan on doing: building 100 blogs but have them ALL pointing to my best-converting paysite ErosExotica. (
www.erosexotica.com) That site converts at about 1:400-500 so with 20k hits to THAT paysite I would expect 30-40 sales.